New guy to the forum. Just purchased my first f/s bike after riding a Klien hardtail for years. I bought a 2002 19" Gary Fisher Sugar 3+ Disc in excellent condition for $750. Is that a good deal?

Also, the stock rear Cane Creek AD 5 Air shock is still on it. With a max travel setting of 4.1" what are my options for a shock upgrade. I know absolutely nothing about rear shocks and the specs. Any particular models anyone can reccomend with model number would be fantastic! I'd really like a Fox Float RP3 but dont know which one to be looking for. I'm 6' and 200lbs.